ext4: fix reading leftover inlined symlinks

Since commit 6493792d3299 ("ext4: convert symlink external data block
mapping to bdev"), create new symlink with inline_data is not supported,
but it missing to handle the leftover inlined symlinks, which could
cause below error message and fail to read symlink.

 ls: cannot read symbolic link 'foo': Structure needs cleaning

 EXT4-fs error (device sda): ext4_map_blocks:605: inode #12: block
 2021161080: comm ls: lblock 0 mapped to illegal pblock 2021161080
 (length 1)

Fix this regression by adding ext4_read_inline_link(), which read the
inline data directly and convert it through a kmalloced buffer.

Fixes: 6493792d3299 ("ext4: convert symlink external data block mapping to bdev")
Cc: stable@kernel.org
Reported-by: Torge Matthies <openglfreak@googlemail.com>
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Tested-by: Torge Matthies <openglfreak@googlemail.com>
Link: https://lore.kernel.org/r/20220630090100.2769490-1-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 15 insertions, 0 deletions

diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c
index d281f5bcc526..3d3ed3c38f56 100644
--- a/fs/ext4/symlink.c
+++ b/fs/ext4/symlink.c
@@ -74,6 +74,21 @@ static const char *ext4_get_link(struct dentry *dentry, struct inode *inode,
 				 struct delayed_call *callback)
 {
 	struct buffer_head *bh;
+	char *inline_link;
+
+	/*
+	 * Create a new inlined symlink is not supported, just provide a
+	 * method to read the leftovers.
+	 */
+	if (ext4_has_inline_data(inode)) {
+		if (!dentry)
+			return ERR_PTR(-ECHILD);
+
+		inline_link = ext4_read_inline_link(inode);
+		if (!IS_ERR(inline_link))
+			set_delayed_call(callback, kfree_link, inline_link);
+		return inline_link;
+	}
 
 	if (!dentry) {
 		bh = ext4_getblk(NULL, inode, 0, EXT4_GET_BLOCKS_CACHED_NOWAIT);